Raw model output on the native 0.25° grid — no MOS, no bias correction, no post-processing. Scores understate operational forecast quality. Read the fairness statement →

CastCheck methodology v0.2 · data through 2026-08-30

San Francisco Intl · NCEP GFS · lead day 7

KSFO · gfs · lead 7

Target day = initialization date + 7 days. This page is a permanent link: the numbers change as history accumulates, the address and the methodology version do not.

Scores use the latest model version segment, gfs-0p25, starting 2026-08-01 — days before that ran a different version of the model and are excluded rather than silently pooled. Of the scored days, 1 carry a QC flag on the observation.

JSON for this page CSV of the daily errors Cite this page

Every number for this combination

All four windows × both initializations × both interpolations × both variables. Errors are computed in °C and shown in °F; CI is a 95 % moving-block bootstrap interval. MAE debiased and skill, debiased remove the constant offset of the window first, so a station that the model always reads a degree too warm is not scored as if it had no skill — compare the two skill columns to see how much of the error is a fixed offset. n QC next to n counts days whose observation carries a QC flag.

VariableInitMethod Windown MAE °F MAE debiased Bias °F RMSE °F ±1 °F±2 °F±3 °F Skill Skill, debiased Period
tmax00Zbilinear30d23 1 QC4.86 [3.76, 5.86]2.96-4.73 [-5.72, -3.60]5.83 [4.49, 6.83]9% [0%, 23%]26%39%-0.35+0.162026-08-08 → 2026-08-30
tmax00Zbilinear90d23 1 QC4.86 [3.53, 5.88]2.96-4.73 [-5.72, -3.36]5.83 [4.07, 6.88]9% [0%, 29%]26%39%-0.35+0.162026-08-08 → 2026-08-30
tmax00Zbilinear365d23 1 QC4.86 [3.40, 5.90]2.96-4.73 [-5.78, -3.23]5.83 [3.91, 6.84]9% [0%, 29%]26%39%-0.35+0.162026-08-08 → 2026-08-30
tmax00Zbilinearall23 1 QC4.86 [3.31, 5.90]2.96-4.73 [-5.75, -3.20]5.83 [4.03, 6.83]9% [0%, 28%]26%39%-0.35+0.162026-08-08 → 2026-08-30
tmax00Znearest30d23 1 QC3.13 [2.22, 4.12]3.12-0.12 [-1.00, 0.97]3.64 [2.68, 4.48]17% [0%, 32%]30%48%+0.13+0.112026-08-08 → 2026-08-30
tmax00Znearest90d23 1 QC3.13 [2.11, 4.20]3.12-0.12 [-0.93, 1.20]3.64 [2.61, 4.57]17% [0%, 33%]30%48%+0.13+0.112026-08-08 → 2026-08-30
tmax00Znearest365d23 1 QC3.13 [1.95, 4.22]3.12-0.12 [-0.94, 1.21]3.64 [2.50, 4.55]17% [0%, 36%]30%48%+0.13+0.112026-08-08 → 2026-08-30
tmax00Znearestall23 1 QC3.13 [2.06, 4.20]3.12-0.12 [-1.01, 1.55]3.64 [2.53, 4.55]17% [0%, 32%]30%48%+0.13+0.112026-08-08 → 2026-08-30
tmax12Zbilinear30d23 1 QC4.94 [3.99, 5.83]2.66-4.81 [-5.67, -3.84]5.87 [4.65, 6.82]9% [0%, 19%]13%35%-0.37+0.242026-08-08 → 2026-08-30
tmax12Zbilinear90d23 1 QC4.94 [3.75, 5.89]2.66-4.81 [-5.74, -3.54]5.87 [4.34, 6.90]9% [0%, 20%]13%35%-0.37+0.242026-08-08 → 2026-08-30
tmax12Zbilinear365d23 1 QC4.94 [3.76, 5.82]2.66-4.81 [-5.63, -3.61]5.87 [4.21, 6.78]9% [0%, 20%]13%35%-0.37+0.242026-08-08 → 2026-08-30
tmax12Zbilinearall23 1 QC4.94 [3.85, 5.89]2.66-4.81 [-5.71, -3.62]5.87 [4.31, 6.83]9% [0%, 20%]13%35%-0.37+0.242026-08-08 → 2026-08-30
tmax12Znearest30d23 1 QC3.11 [2.38, 3.86]3.11-0.14 [-1.00, 1.03]3.78 [2.87, 4.53]22% [11%, 32%]35%61%+0.14+0.112026-08-08 → 2026-08-30
tmax12Znearest90d23 1 QC3.11 [2.36, 3.91]3.11-0.14 [-1.05, 1.31]3.78 [2.84, 4.56]22% [8%, 33%]35%61%+0.14+0.112026-08-08 → 2026-08-30
tmax12Znearest365d23 1 QC3.11 [2.29, 3.87]3.11-0.14 [-1.06, 1.26]3.78 [2.74, 4.62]22% [8%, 33%]35%61%+0.14+0.112026-08-08 → 2026-08-30
tmax12Znearestall23 1 QC3.11 [2.30, 3.87]3.11-0.14 [-1.09, 1.27]3.78 [2.79, 4.62]22% [7%, 33%]35%61%+0.14+0.112026-08-08 → 2026-08-30
tmin00Zbilinear30d23 1 QC1.15 [0.97, 1.32]1.04-0.41 [-0.98, 0.10]1.28 [1.12, 1.41]43% [22%, 67%]96%100%-0.02+0.082026-08-08 → 2026-08-30
tmin00Zbilinear90d23 1 QC1.15 [0.97, 1.33]1.04-0.41 [-1.11, 0.14]1.28 [1.12, 1.43]43% [22%, 68%]96%100%-0.02+0.082026-08-08 → 2026-08-30
tmin00Zbilinear365d23 1 QC1.15 [0.95, 1.34]1.04-0.41 [-1.09, 0.17]1.28 [1.11, 1.43]43% [20%, 71%]96%100%-0.02+0.082026-08-08 → 2026-08-30
tmin00Zbilinearall23 1 QC1.15 [0.96, 1.33]1.04-0.41 [-1.05, 0.11]1.28 [1.12, 1.42]43% [20%, 71%]96%100%-0.02+0.082026-08-08 → 2026-08-30
tmin00Znearest30d23 1 QC2.07 [1.71, 2.54]1.16-1.84 [-2.45, -1.28]2.33 [1.93, 2.76]22% [9%, 35%]52%78%-0.83-0.032026-08-08 → 2026-08-30
tmin00Znearest90d23 1 QC2.07 [1.67, 2.63]1.16-1.84 [-2.62, -1.28]2.33 [1.90, 2.83]22% [6%, 35%]52%78%-0.83-0.032026-08-08 → 2026-08-30
tmin00Znearest365d23 1 QC2.07 [1.66, 2.62]1.16-1.84 [-2.58, -1.24]2.33 [1.87, 2.81]22% [5%, 36%]52%78%-0.83-0.032026-08-08 → 2026-08-30
tmin00Znearestall23 1 QC2.07 [1.68, 2.62]1.16-1.84 [-2.58, -1.27]2.33 [1.93, 2.82]22% [5%, 36%]52%78%-0.83-0.032026-08-08 → 2026-08-30
tmin12Zbilinear30d23 1 QC0.98 [0.79, 1.23]0.76-0.63 [-1.02, -0.24]1.12 [0.93, 1.31]48% [25%, 64%]96%100%+0.13+0.332026-08-08 → 2026-08-30
tmin12Zbilinear90d23 1 QC0.98 [0.76, 1.32]0.76-0.63 [-1.14, -0.17]1.12 [0.90, 1.36]48% [19%, 65%]96%100%+0.13+0.332026-08-08 → 2026-08-30
tmin12Zbilinear365d23 1 QC0.98 [0.76, 1.31]0.76-0.63 [-1.16, -0.15]1.12 [0.89, 1.36]48% [20%, 66%]96%100%+0.13+0.332026-08-08 → 2026-08-30
tmin12Zbilinearall23 1 QC0.98 [0.78, 1.31]0.76-0.63 [-1.14, -0.17]1.12 [0.91, 1.35]48% [21%, 64%]96%100%+0.13+0.332026-08-08 → 2026-08-30
tmin12Znearest30d23 1 QC2.26 [1.97, 2.58]0.88-2.23 [-2.55, -1.94]2.49 [2.27, 2.74]22% [8%, 35%]26%74%-1.00+0.222026-08-08 → 2026-08-30
tmin12Znearest90d23 1 QC2.26 [1.93, 2.64]0.88-2.23 [-2.63, -1.90]2.49 [2.27, 2.79]22% [6%, 34%]26%74%-1.00+0.222026-08-08 → 2026-08-30
tmin12Znearest365d23 1 QC2.26 [1.90, 2.63]0.88-2.23 [-2.60, -1.87]2.49 [2.23, 2.77]22% [5%, 38%]26%74%-1.00+0.222026-08-08 → 2026-08-30
tmin12Znearestall23 1 QC2.26 [1.93, 2.67]0.88-2.23 [-2.65, -1.89]2.49 [2.24, 2.78]22% [5%, 35%]26%74%-1.00+0.222026-08-08 → 2026-08-30

+ model too warm · − model too cold · bias interval includes zero · ★ lowest MAE · = not distinguishable from the leader · ▼ significantly worse · n < 30 greyed and unranked · CI is a 95 % moving-block bootstrap interval.

Daily error, last 90 days

Daily forecast minus observed error in °F for NCEP GFS at KSFO, lead day 7, 00Z bilinear tmax+20+100-10-202026-08-08: +0.96 °F2026-08-09: -3.9 °F2026-08-10: -8.68 °F2026-08-11: -9.44 °F2026-08-12: -9.31 °F2026-08-13: -2.52 °F2026-08-14: -1.53 °F2026-08-15: -1.51 °F2026-08-16: -3.23 °F2026-08-17: -6.16 °F2026-08-18: -3.62 °F2026-08-19: -1.27 °F2026-08-20: -5.34 °F2026-08-21: -4.08 °F2026-08-22: -2.75 °F2026-08-23: -10.05 °F2026-08-24: -6.68 °F2026-08-25: -1.84 °F2026-08-26: -11.17 °F2026-08-27: -8.1 °F2026-08-28: +0.46 °F2026-08-29: -2.71 °F2026-08-30: -6.41 °F2026-08-082026-08-30°F, forecast − observed
Forecast − observed, °F, 00Z bilinear daily maximum. The dashed line is zero; the thick line is a centred 7-day mean, drawn only where the whole window is present. Gaps are days with no score, never interpolation. Hover a point for its date and value.
The same series as a table (23 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-6.41
2026-08-29-2.71
2026-08-28+0.46
2026-08-27-8.10
2026-08-26-11.17
2026-08-25-1.84
2026-08-24-6.68
2026-08-23-10.05
2026-08-22-2.75
2026-08-21-4.08
2026-08-20-5.34
2026-08-19-1.27
2026-08-18-3.62
2026-08-17-6.16
2026-08-16-3.23
2026-08-15-1.51
2026-08-14-1.53
2026-08-13-2.52
2026-08-12-9.31
2026-08-11-9.44
2026-08-10-8.68
2026-08-09-3.90
2026-08-08+0.96

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KSFO, lead day 7-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 0 days-12 to -10 °F: 2 days-10 to -8 °F: 4 days-8 to -6 °F: 3 days-6 to -4 °F: 2 days-4 to -2 °F: 6 days-2 to 0 °F: 4 days0 to 2 °F: 2 days2 to 4 °F: 0 days4 to 6 °F: 0 days6 to 8 °F: 0 days8 to 10 °F: 0 days10 to 12 °F: 0 days12 to 14 °F: 0 days14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 3.9 · P90 |e| 9.41 °F-200+20 °Fn = 23 days
All scored days for 00Z bilinear daily maximum, 20 equal bins. The dashed marks are the 50th and 90th percentiles of the absolute error, mirrored on both sides. Hover a bar for its bin and count.
Bin counts as a table
From °FTo °FDays
-20.00-18.000
-18.00-16.000
-16.00-14.000
-14.00-12.000
-12.00-10.002
-10.00-8.004
-8.00-6.003
-6.00-4.002
-4.00-2.006
-2.00+0.004
+0.00+2.002
+2.00+4.000
+4.00+6.000
+6.00+8.000
+8.00+10.000
+10.00+12.000
+12.00+14.000
+14.00+16.000
+16.00+18.000
+18.00+20.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08234.86 -4.73

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-08 → 2026-08-30 23
NCEP GFS2026-08-08 → 2026-08-30 23
NCEP GFS2026-08-08 → 2026-08-30 23
NCEP GFS2026-08-08 → 2026-08-30 23

Compared with other models

Paired bootstrap on the days both models cover (90d, 00Z, bilinear, daily maximum). Negative means NCEP GFS has the lower MAE. "Distinguishable" means the 95 % interval excludes zero.

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 23 -0.48 [-1.39, 0.25] no
GraphCast (IFS init) 23 -1.09 [-2.50, 0.44] no
ECMWF IFS HRES 18 -1.11 [-1.58, -0.34] yes
Persistence (baseline) 23 +1.25 [-0.67, 2.37] no

Cite this page

ShortCastCheck, KSFO gfs lead 7, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSFO/model/gfs/lead/7/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSFO (San Francisco Intl), model gfs, lead day 7. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KSFO/model/gfs/lead/7/

Accessed2026-08-31 (data through 2026-08-30; page built 2026-08-31T03:52:06+00:00)

JSON CSV all scores methodology v0.2 licence